A vapor pressure method for the simultaneous determination of standard thermodynamic functions of both solutes in a ternary dilute solution

1978 ◽  
Vol 56 (6) ◽  
pp. 844-847 ◽  
Author(s):  
Claude Treiner ◽  
Pierre Tzias ◽  
Marius Chemla
Keyword(s):  
Aqueous Solution ◽  
Free Energy ◽  
Vapor Pressure ◽  
Tetrabutylammonium Bromide ◽  
Ternary Mixtures ◽  
Binary Solvents ◽  
Volatile Components ◽  
Polar Group ◽  
Free Energy Of Transfer ◽  
Energy Of Transfer

It is shown that from vapor pressure measurements on dilute solutions of ternary mixtures with one nonvolatile component, the standard free energy of transfer (ΔGt0) of both solutes from water to aqueous binary solvents can be determined simultaneously. The method is most useful in the case of volatile components. ΔGt0 values are discussed in particular in the case of the transfer of tetrahydrofuran, acetone, and acetonitrile from water to aqueous tetrabutylammonium bromide and urea solutions and compared to the case of the transfer of nonpolar solutes to the same aqueous solution. In each case, the free energy of transfer from water to an aqueous solution of a nonpolar molecule was negative, and introduction in that molecule of a polar group caused the free energy of transfer to be considerably less negative.

scholarly journals HYDROPHOBIC EFFECTS IN WATER AND WATER/UREA SOLUTIONS A COMPARISON

1994 ◽  
Vol 2 (2) ◽  
pp. 71-82
Author(s):  
E. A. Lissi ◽  
E. B. Abuin
Keyword(s):  
Aqueous Solution ◽  
Free Energy ◽  
Alkyl Chain ◽  
Standard Free Energy ◽  
The Other ◽  
Standard Entropy ◽  
Simple Description ◽  
Free Energy Of Transfer ◽  
Energy Of Transfer ◽  
Entropy Of Transfer

The partition of several n-alkanols, from methanol to n-nonanol, between n-hexane and water and between n-hexane and water containing 20 % (w/v) urea has been measured at temperatures ranging from 0 °C to 60 °C. The standard free energy of transfer from water to the urea-containing solution decreases with the length of the alkyl chain, being positive for the small alcohols and negative for the higher alkanols. The same tendency is observed upon all the temperature range considered. On the other hand, the standard entropy of transfer from water to the urea-containing solution increases with the length of the alkyl chain of the alkanol. These results are compatible with a simple description of the urea effect in terms of increasing the entropy of dissolution of the hydrophobic alkyl chain in the aqueous solution.

Thermodynamics of transfer of Ph4C; scaled-particle theory and the Ph4As+/Ph4B− assumption for single ions

1979 ◽  
Vol 57 (15) ◽  
pp. 2004-2009 ◽  
Author(s):  
Michael H. Abraham ◽  
Asadollah Nasehzadeh
Keyword(s):  
Free Energy ◽  
Total Free Energy ◽  
Scaled Particle Theory ◽  
Free Energies ◽  
Particle Theory ◽  
Free Energy Of Transfer ◽  
Enthalpy And Entropy ◽  
Interaction Term ◽  
Energy Of Transfer ◽  
Entropy Of Transfer

Free energies of transfer of Ph4C from acetonitrile to 20 other solvents have been calculated from literature data. The contribution of the cavity term to the total free energy has been obtained from scaled-particle theory and Sinanoglu–Reisse–Moura Ramos theory. It is shown that there is little connection between the cavity term and the total free energy of transfer, and that there must be, in general, a large interaction term. If the latter is important for transfer of Ph4C, we argue that it must also be important for transfer of the ions Ph4As+ and Ph4B−. Previous suggestions that the interaction term is zero for transfer of these two ions are thus seen to be unreasonable. We also show, for six solvents, that the interaction term for Ph4C is very large in terms of enthalpy and entropy, and that scaled-particle theory seems not to apply to transfers of Ph4C between pure organic solvents.The free energy, enthalpy, and entropy of transfer of Ph4As+ = Ph4B− have been calculated by dividing the total transfer values into neutral and electrostatic contributions; reasonable agreement is obtained between calculated and observed values.

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